Abstract: A method for estimating a probability of failure of a least-squares ambiguity decorrelation adjustment (LAMBDA) method is provided. The LAMBDA method is used for estimation of double difference carrier phase integer ambiguity. A plurality of condition sets are selected. Each condition set comprises a probability of failure (Pboot-fail) for a boot-strap method of estimation of the double difference carrier phase integer ambiguity, a number of space vehicles (Nsv), and a ratio test tolerance for the LAMBDA method. A plurality of Monte Carlo simulations are run on the plurality of condition sets to obtain a plurality of result sets. Each result set comprises a probability of lambda fail (P?-fail) and a probability of lambda reject (P?-reject) for one condition set of the plurality of condition sets. A lookup table is created with the plurality of result sets. A value of P?-fail for given values of P?-reject, Pboot-fail, and Nsv is estimated through employment of the lookup table.

Abstract: A method for estimating a probability of failure of a least-squares ambiguity decorrelation adjustment (LAMBDA) method is provided. The LAMBDA method is used for estimation of double difference carrier phase integer ambiguity. A plurality of condition sets are selected. Each condition set comprises a probability of failure (Pboot-fail) for a boot-strap method of estimation of the double difference carrier phase integer ambiguity, a number of space vehicles (Nsv), and a ratio test tolerance for the LAMBDA method. A plurality of Monte Carlo simulations are run on the plurality of condition sets to obtain a plurality of result sets. Each result set comprises a probability of lambda fail (P?-fail) and a probability of lambda reject (P?-reject) for one condition set of the plurality of condition sets. A lookup table is created with the plurality of result sets. A value of P?-fail for given values of P?-reject, Pboot-fail, and Nsv is estimated through employment of the lookup table.

Abstract: A method for attitude alignment of a slave inertial measurement system connected to a rotationally mobile platform supported by a vehicle that is stationary relative to a reference navigation frame comprises the steps of mounting a master reference inertial measurement system on the rotationally mobile platform and determining a master reference system attitude using measurements of acceleration and angular rates of the master reference inertial measurement system relative to the reference navigation frame. A slave system attitude is determined using measurements of acceleration and angular rates of the slave inertial measurement system relative to a slave system navigation reference frame and comparing the slave system attitude to the master reference system attitude to determine an attitude difference. The attitude difference is processed to obtain a correction to the slave system attitude.

Abstract: A phase error and/or amplitude error of a global positioning system carrier signal is estimated through employment of an optimal minimum variance of the global positioning system carrier signal.

Abstract: A projectile guidance system without gyros in which the projectile has an orthogonal body coordinate system. The projectile has a triax of accelerometers providing x, y and z acceleration data measured along the x, y and z axes respectively. A GPS antenna and receiver means provides onboard GPS position and velocity data in earth referenced navigational coordinates. A computer and program means stores and accesses time indexed GPS position and GPS velocity data and transforms x, y and z axis acceleration data from body to navigation coordinates. The program means is responsive to corresponding time indexed acceleration data and to GPS velocity and position data for calculating and outputting an estimated projectile roll, pitch and yaw angle via optimal smoothing techniques with respect to local level for each time index iteration of present position to a flight control system, which actuates a divert propulsion system for guiding the projectile to a predetermined location.

Abstract: A projectile guidance system without gyros in which the projectile has an orthogonal body coordinate system. The projectile has a triax of accelerometers providing x, y and z acceleration data measured along the x, y and z axes respectively. A GPS antenna and receiver means provides onboard GPS position and velocity data in earth referenced navigational coordinates. A computer and program means stores and accesses time indexed GPS position and GPS velocity data and transforms x, y and z axis acceleration data from body to navigation coordinates. The program means is responsive to corresponding time indexed acceleration data and to GPS velocity and position data for calculating and outputting an estimated projectile roll, pitch and yaw angle via optimal smoothing techniques with respect to local level for each time index iteration of present position to a flight control system, which actuates a divert propulsion system for guiding the projectile to a predetermined location.

Abstract: A method for attitude alignment of a slave inertial measurement system connected to a rotationally mobile platform supported by a vehicle that is stationary relative to a reference navigation frame comprises the steps of mounting a master reference inertial measurement system on the rotationally mobile platform and determining a master reference system attitude using measurements of acceleration and angular rates of the master reference inertial measurement system relative to the reference navigation frame. A slave system attitude is determined using measurements of acceleration and angular rates of the slave inertial measurement system relative to a slave system navigation reference frame and comparing the slave system attitude to the master reference system attitude to determine an attitude difference. The attitude difference is processed to obtain a correction to the slave system attitude.

Abstract: The invention is a method continuing over a plurality of time periods for compensating for the output error in each of one or more navigation instruments in a system comprising a plurality of navigation instruments after the system is introduced into its operating environment. The practice of the method begins with determining the values of one or more of a set of coordinates that specify the position, velocity, and orientation of the system in space together with the error in a compensated output for each of the one or more navigation instruments. The method continues with determining a compensation model for each of the one or more navigation instruments. A compensation model specifies for a current time period an adjustment in amplitude of the output of a navigation instrument as a function of time and temperature.

Abstract: The present invention is a method and apparatus for detecting torpedo guidance system failures which are likely to cause the torpedo to make a circular run. The method consists of measuring the yaw-axis angular velocity of the torpedo and comparing this measurement with a computed estimate of the yaw-axis angular velocity based on measurements of torpedo dynamics other than the yaw-axis angular velocity. If the difference between the measured and computed values exceeds a threshold value, the presumption is that the torpedo is in a circular run and should be destroyed. The invention envisions various levels of precision in computing the estimate of the yaw-axis angular velocity. The various levels of precision involve the measurement of one or more of the group of dynamics parameters consisting of the three components of acceleration and the two components of angular velocity along the pitch and roll axes.

Abstract: The invention is a method for determining the relative position and velocity of a second vehicle with respect to a first vehicle. The method is practiced on board the second vehicle and utilizes a plurality of satellite transmitters and an inertial measurement unit on the second vehicle. The first vehicle has available a plurality of data items consisting of the first vehicle's measured position, measured velocity, and specific-force acceleration. The second vehicle has available data items consisting of the second vehicle's measured position, measured velocity, specific-force acceleration, autonomous position, autonomous velocity, autonomous position correction, and autonomous velocity correction. The measured position and measured velocity are determined utilizing the radio signals from a plurality of satellite transmitters and the specific-force acceleration is obtained from an inertial measurement unit.

Abstract: The invention is a method for obtaining observables for input to a Kalman filter process which determines the attitude (roll, pitch, and heading) of a platform. The invention utilizes an inertial measurement unit (IMU) attached to the platform and an associated processor, a plurality of signal receiving antennas attached to the platform, and a plurality of satellite transmitters. The heading of the platform as determined by the IMU and its associated processor by themselves can be significantly in error. A comparison of the values of an attitude-sensitive function of the ranges from the platform antennas to different groupings of satellite transmitters obtained first by using IMU data and second by using the measured phases of the satellite-transmitter signals received at the platform antennas, a very accurate value for the range function is obtained. This accurate value of the range function is used in a Kalman filter process to obtain very accurate values for platform attitude.

Abstract: The navigation apparatus with improved attitude determination is intended for use on a mobile platform. It combines data from a platform inertial navigation unit and carrier phase data for a plurality of GPS satellite signals received at a plurality of receiving points on the platform for the purpose of obtaining estimates of the navigation states of the platform. The navigation apparatus comprises a processor which computes estimates of the states from inputs comprising (1) one or more measured phase double-differences calculated from the measured satellite signal carrier phases, (2) the estimated position of the platform, (3) the estimated positions of the receiving points, and (4) the positions of the satellites, a phase double-difference being defined as the difference in phase differences for signals received from two satellites and a phase difference being defined as the difference in carrier phase of a satellite signal received at two receiving points.